Abstract/Project Summary: The cell cycle is critical for health and disease. Defects in the cell cycle result in disruptions in morphogenetic behaviors as well as cancer. In order to understand how the cell cycle impinges on morphogenetic and disease processes, I am developing a fluorescence cell cycle state biosensor for use in C. elegans. This cell cycle state biosensor is dynamically localized between the nucleus and cytoplasm over the course of the cell cyle via cyclin dependent kinase activity. Ratiometric measurement of the cytoplasm and nucleus allows for direct quantification of cell cycle state. Additionally, I am developing a software package for automated image analysis of ratiometric data for use in C. elegans. As a test case, I will characterize the cell cycle in the morphogenesis of the C. elegans vulva and uterus. One of the cells in the uterus, the anchor cell, invades through two layers of basement membrane to contact the underlying vulval epithelium, forming the connection between the uterus and the vulva required for ovoposition and initiating vulval morphogenesis. The anchor cell can only invade the basement membrane in G1/G0?a cell cycle state that may be broadly associated with the ability to breach the basement membrane in both cancer metastasis and development. This cell cycle arrest is mediated by both cell cycle components and chromatin modifiers. Using the cell cycle indicator developed by this proposal, I will identify the genetic mechanism by which the G1/G0 pro- invasive cell cycle arrest of the anchor cell is maintained.